Numerical Control Machine Vibration Suppression via Speed Ratio
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Solution Overview
Problem
In numerical control machines, disparities in acceleration/deceleration control between the main spindle and feed axis lead to phase differences in rotational speed and feed rate fluctuations, causing inconsistent cutting feed amounts and surface quality issues like stripes on processed surfaces.
Innovation Solution
A numerical control machine with a vibration suppression unit that calculates and maintains a constant ratio between main spindle rotational speed and feed axis feed rate, using a delay time calculation unit to adjust the feed rate based on actual and estimated rotational speeds to minimize phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the rotational speed of the main spindle is fluctuated to suppress chattering vibrations, then vibration suppression is improved, but phase difference with feed axis occurs causing non-uniform cutting surfaces
Solution Approach 1:
The system uses feedback control by detecting the actual rotational speed of the main spindle and using this information to adjust the feed axis speed. The feedback control unit calculates the ratio between the commanded feed axis speed and the actual main spindle speed, and adjusts the feed axis commanded speed to maintain a constant cutting feed amount per rotation, thereby eliminating phase difference and ensuring uniform cutting surfaces while suppressing chattering vibrations.
Solution Approach 2:
The system dynamically changes the feed axis speed parameter based on the actual main spindle rotational speed. By continuously adjusting the feed axis commanded speed according to the detected main spindle speed fluctuations, the system maintains a constant ratio between feed rate and rotational speed, ensuring uniform cutting conditions even when the main spindle speed is fluctuated for vibration suppression.
2Manufacturing precision
If constant acceleration/deceleration time control is applied to feed axis to ensure path accuracy, then positioning precision is improved, but time lag relative to main spindle occurs
Solution Approach 1:
The system performs preliminary calculation of the appropriate feed axis speed based on the detected main spindle speed before executing the movement. By calculating the required feed axis commanded speed in advance based on the current main spindle rotational speed and the desired constant ratio, the system compensates for time lag and ensures synchronized operation between the main spindle and feed axis during acceleration and deceleration phases.
3Manufacturing precision
If feed axis speed is adjusted based on sensed main spindle speed, then cutting feed consistency is improved, but time lag between sensing and response occurs
Solution Approach 1:
The system implements real-time feedback control where the feedback control unit continuously monitors the actual main spindle rotational speed and immediately adjusts the feed axis commanded speed to maintain the constant ratio. This closed-loop feedback mechanism minimizes response time lag by continuously updating the feed axis speed based on the latest detected main spindle speed, ensuring consistent cutting feed despite the inherent time lag in the control system.
Data Source
AI summary
A numerical control machine estimates a future rotational speed ahead by a delay time that is a phase difference between a rotational speed fluctuation of a main spindle and a feed rate fluctuation of a feed axis, and fluctuates the feed rate such that a constant ratio is maintained with the estimated rotational speed.